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[rhea]

can some1 explain vernier calipers

[Raywin]

can some1 explain vernier calipers

Its an instrument that is used to measure (accurately) the thickness of something REALLY small like a coin which for example a ruler cannot measure accurately. 

[Ghost Of Highbury]

Thanks a lot!!    and another thing wht is the relationship between the resistance of a wire and its length and diameter?

The resistance of the wire is inversely proportional to the diameter, better to say the cross-sectional area and directly proportional to the length;

[Vin]

Aadi two ques for you .. either im too dumb or the ms is wrong ..

for the first one .. i know its not in the 2010 syllabus i jus wanna know..

fo the 2nd .. i knoe tht the resistance increases in dark but y does pd increase ??..i ve been trying to figure out since long now!

[Raywin]

The resistance of the wire is inversely proportional to the diameter, better to say the cross-sectional area and directly proportional to the length;

Thank you once again!  

[igext]

Interesting Question:
In a transformer the induced current in the 2ndry coil also has a mgnetic field right?
then why isnt the current in the primary coil affected?

[rhea]

Its an instrument that is used to measure (accurately) the thickness of something REALLY small like a coin which for example a ruler cannot measure accurately. 

to what dp does it measure?
also can it be used to measure a pipe?

[Adzel]

@ VIN: the resistance is always directly proportional to the P.D...

[Ghost Of Highbury]

Aadi two ques for you .. either im too dumb or the ms is wrong ..

for the first one .. i know its not in the 2010 syllabus i jus wanna know..

fo the 2nd .. i knoe tht the resistance increases in dark but y does pd increase ??..i ve been trying to figure out since long now!

for the first one : what is the answer , is it B?

for the second, V = I*R

R increases, V increases

thats wat i can think of now.

[Vin]

Interesting Question:
In a transformer the induced current in the 2ndry coil also has a mgnetic field right?
then why isnt the current in the primary coil affected?

Induced current is produced when the mag. field from the Primary coils 'cuts' the secondary.
When the current is switched off in the primary the mag field dies away therefore cutting secondary as they collapse inducing a pd into it. tht is why a.c is used

[Vin]

for the first one : what is the answer , is it B?

for the second, V = I*R

R increases, V increases

thats wat i can think of now.

ya how B ? y- axis thts y??

but when R increases, doesnt the value of the current in the circuit in the change ??

[Raywin]

to what dp does it measure?
also can it be used to measure a pipe?

Hmmm... Vernier calipers can measure internal dimensions (using the uppermost jaws in the picture given), external dimensions using the pictured lower jaws, depth measurements by the use of a probe that is attached to the movable head and slides along the centre of the body. This probe is slender and can get into deep grooves that may prove difficult for other measuring tools.
The vernier scales may include both metric and inch measurements on the upper and lower part of the scale.
Vernier calipers commonly used in industry provide a precision to a hundredth of a millimetre (10 micrometres), or one thousandth of an inch.
A more precise instrument used for the same purpose is the micrometer. I hope this info helps googled it.. check the picture attached..

[8T]

Is any1 free enough to post for me the electromagnetic spectrum in order of frequency and wavelenth .
I know that one goes opposite to the other .
Plus,an explanation of total internal reflection is helpful too.
Thanks in advance.

[rhea]

whats the use of a
split ring commutator
slip ring commutator?

IN DETAIL please?
 

[Ghost Of Highbury]

ya how B ? y- axis thts y??

but when R increases, doesnt the value of the current in the circuit in the change ??

Nah, i dont think it changes..the share of the voltage received decreases.

and abt that. The time base is the x-axis. The a/c current produces the y-axis.

--------                           |
                                      |    <- only a.c current
only time base                   |    
                                      |

when they combine they form the wave.